1. Field of the Invention:
Construction equipment such as front end loaders can be adapted to forestry operations such as tree harvesting by the provision of a shearing head or shear mechanism at a forward end thereof. The shear mechanism comprises power driven means for readily cutting and felling a tree in logging operations. The shear mechanism normally employs a pair of cutting blades which can be activated by one or more hydraulic cylinders to draw the blades together and shear off the tree. The shear mechanism is generally provided at the base portion of a supporting column which carries the power means for driving the shear blade and generally provides a grapple mechanism in spaced relation from the shear mechanism, the grapple mechanism being employed to hold the tree in abutting relation with the supporting column while the tree is being cut by the shear mechanism. Although the shear and grapple combination substantially improves the operating efficiency of a logging operation and permits discrete placement of felled trees, it is desirable to provide the harvesting machine with the capability to accumulate trees as they are being cut. This is particularly true in the pulp and paper industry where the vast majority of trees cut are of relatively small diameter and the initial logging process can be substantially accelerated if the machine has the capability to gather trees thereon as they are being cut to be later deposited in a central pick up area. To this end a number of accumulator mechanisms have been employed.
2. History of the Prior Art
Typical of the prior art is the U.S. Pat. No. 3,805,860 -- Smith, entitled "Apparatus for Severing and Grouping Trees" wherein a gathering finger is employed in conjunction with a shear and accumulating mechanism to accumulate sheared trees. The mechanism employs articulated gripping finger parts which form an articulated holding finger for holding severed trees while a successive tree to be severed and grouped therewith is held against the holding finger. Separate withdrawing forces requiring two powered means are applied to the finger parts to "snake" the parts out to a removed position permitting the trees to be grouped. The grouped trees can then be deposited on the ground in position to be picked up by other equipment.
The above patent is typical of a group of prior art which requires that the gathering arm of the accumulator be articulated or jointed at some intermediate portion thereof so as to enable the arm to be removed from between the last cut tree and the group of trees already accumulated in order to gather the freshly cut tree into the group of accumulated trees. The present invention disposes of multiple power means to perform the so-called "snaking" motion and further provides a uniform accumulator arm having an involute outer surface which permits the arm to be readily withdrawn from between the accumulted trees and the newly cut tree and to be returned to place, bunching all trees, such involute arm not requiring an intermediate movable section.
The advantages of such an accumulator arm are obvious. Multiple power sources operating the arm are eliminated, pivotal joints required in the arm are eliminated and the accumulating function becomes greatly simplified.
Other objects and advantages of the present invention will become apparent as the description thereof proceeds.